sysdeps/alpha/fpu/fesetenv.c

   1 /* Install given floating-point environment.
   2    Copyright (C) 1997, 1999 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Richard Henderson <rth@tamu.edu>, 1997
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <fenv.h>
  22
  23 int
  24 __fesetenv (const fenv_t *envp)
  25 {
  26   unsigned long int fpcr;
  27   fenv_t env;
  28
  29   /* Magic encoding of default values: high bit set (never possible for a
  30      user-space address) is not indirect.  And we don't even have to get
  31      rid of it since we mask things around just below.  */
  32   if ((long int) envp >= 0)
  33     env = *envp;
  34   else
  35     env = (unsigned long int) envp;
  36
  37   /* Reset the rounding mode with the hardware fpcr.  Note that the following
  38      system call is an implied trap barrier for our modification.  */
  39   __asm__ __volatile__ ("excb; mf_fpcr %0" : "=f" (fpcr));
  40   fpcr = (fpcr & ~(3UL << 58)) | (env & (3UL << 58));
  41   __asm__ __volatile__ ("mt_fpcr %0" : : "f" (fpcr));
  42
  43   /* Reset the exception status and mask with the kernel's FP code.  */
  44   __ieee_set_fp_control (env & (FE_ALL_EXCEPT | 0x3e));
  45
  46   /* Success.  */
  47   return 0;
  48 }
  49 strong_alias (__fesetenv, __old_fesetenv)
  50 symbol_version (__old_fesetenv, fesetenv, GLIBC_2.1);
  51 default_symbol_version (__fesetenv, fesetenv, GLIBC_2.1.3);